Combined double knockout of Ezh2 and G9a leads to expression change in murine retinal ganglion cells

Purpose: The goal of this study is to evaluate H3K27me3 histone marks in retinal ganglion cells in Ezh2 (Math5Cre, Ezh2-/-) and combined G9a-Ezh2 (Math5Cre; G9a+/-Ezh2-/-) knockout mutant mice at P1. Both Ezh2 and G9a are major epigenetic silencing machineries. Ezh2 mediates the trimethylation of lysine 27 on histone 3. Emerging evidences show an interdependence between Ezh2 and G9a to facilitate K27 trimethylation. Methods: P1 retinal ganglion cells were collected and chromatin immunoprecipitation was performed with EZ- CHIP kit from Millipore. Library preparation was done with Rubicon Genomics Thruplex DNAseq. Results: Here, we find a pool of common K27me3 target genes of Ezh2 and G9a in double knockout that leads to dysfunction in double mutant RGCs. Conclusion: This study provides the first Chip-seq analysis of K27me3 in murine RGCs. Our data supports that an interaction between Ezh2 and G9a is also evident in murine retinal ganglion cells. This work should be a framework for further study of retinal ganglion cells and retinal diseases. Overall design: Examination of H3K27me3 marks in single Ezh2 (Math5Cre; Ezh2-/-) and combined G9a-Ezh2 (Math5Cre; G9a+/-Ezh2-/-) knockout murine retinal ganglion cells